1. Field of the Invention
The present invention relates to a parameter estimating method, and more particularly, to a method for estimating motion parameters and angle of a target.
2. Description of Related Art
Following the rapid increase of population and gradual recovery of world economy, disposable personal income and consumption power have increased year by year, which, accordingly, has made the world car sales increase continuously. Statistics show that car sales in most countries increase in 2010 and, in particular, car sales in China mainland hit 18.06 million units, which ranks first, followed by the United States and Japan, with 12 million units and 5 million units, respectively.
With the continuous growth in car sales, the car electronics industry has been in vigorous development which covers six major aspects including car safety system, body system, driver information system, suspension & chassis system, engine transmission system, and security system. Among these aspects, the car safety system has the highest compound annual growth rate.
With the number of cars ever-increasing, the possibilities of road traffic accidents also increase. A European study shows that an extra 0.5 second early warning can prevent at least 60% of rear-end collisions, 30% of head-on collisions and 50% of road-related accidents, and 1.5 seconds will prevent 90% of them. Therefore, the car safety system is critically important.
The car safety system can be classified, in terms of function and types, into active and passive types. Prior to year 2000, the passive safety systems, for example, safe belts or various types of air-bags, were mainly used in the market. Following the development of semiconductor technology and advancement of high frequency electronic circuit technology, the active safety systems have been rapidly developed since year 2000. At the same time, people's demand for safety is continuously rising, which transits from the original passive damage reduction to active damage avoidance. During driving on the road, if the active safety systems can provide the early warning function prior to the occurrence of danger, reminding the driver or even actively manipulating the vehicle to avoid danger to thereby provide protection for the drivers, they can play a better role than the passive safety systems.
Accordingly, current active safety systems have undergone a significant development, which dominate the overall car safety system market. The current active safety systems include, for example, adaptive cruise control (ACC), Stop & Go, lane departure warning system, environment recognition, collision avoidance, advanced driver aid system (ADAS). Developments of the active safety systems in the world generally lie in three major aspects: 1. basic collision-avoidance warning technology—adaptive cruise control, rear end collision-avoidance, frontal pedestrian and obstacle detection; 2. advanced collision-avoidance technology—improper lane change avoidance, avoidance of collision-accidents at the crossroad, and vehicle diagnosis; 3. basic driver information equipment—road guide, instant traffic, driver information and navigation.
Current European governments' study plan focuses on the development of driver monitoring system, road condition detection system and smart steering control. US government is cooperating with General Motor to develop and test a rear view collision avoidance system. Japan is conducting a large amount of on-road verification of Smartway, which employs various sub-systems including a forward radar and a lane departure warning indicator to perform various advanced functions such as cruise, collision avoidance and lane tracking that are expected to be widely implemented in year 2015. In addition, Korea has also planned to complete the road vehicle automation before 2020.
The adaptive cruise control (ACC) of the active safety system is developed mainly toward the trend of fixed speed cruise function, the application of which includes high speed, low speed and all-speed cruise control. The principle of the adapted cruise control is that, during a fixed speed cruise of the vehicle, a radar system installed in the front of the vehicle is used to detect the traffic condition in front of the vehicle to maintain a safe distance. When another vehicle enters the lane such that there is not a sufficient safe distance, the vehicle automatically reduces its speed. When there is a sufficient safe distance in front of the vehicle, the vehicle automatically increases its speed back to the driver-set speed. So far, car manufactures, such as NISSAN, BMW, Mercedes Benz, Lexus, Infiniti or the like, have equipped the adaptive cruise control system in their high-level car models. The Stop & Go system is an advanced version of the adaptive cruise control system, the improvement of which is that it can optionally reduce the speed to stop the car rather than shut off the system function at a specific speed. In addition, the Stop & Go system can also automatically accelerate the car to a preset speed and maintain the car distance when the vehicle ahead moves again, and the preset speed can be automatically adjusted according to the traffic, which is suitable for the congested urban roads.
From the above it can be seen that, in the adaptive cruise control and Stop & Go systems, the forefront collision-avoidance radar is a key part. Once the radar misjudges and provides false information, it will cause the entire system to correspondingly generate an incorrect control manner.
However, the signal processing technology of the common adaptive cruise control usually requires high computational load and long observation time to achieve a certain detection accuracy, which makes the practical application of the adaptive cruise control still unsatisfactory.